SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ad931f134bd5c8bf924a6a7d23817f0113eb0267afb417578c1455c5064130f' 
  AND token = 'ug0VIvQwUls8cB30tN92Y5bv5BS6PSGvkFCdC/aFhCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}